The present invention relates generally to fluid flow control and, more particularly it relates to a device for controlling the flow of fluid out of a fluid collection reservoir. The device is especially suitable for use in the control of the outflow of blood from a blood collection and transfer reservoir.
There have been introduced into the marketplace a number of direct whole blood cardiotomy reservoirs and methods for using reservoirs during the recovery and collection of blood for subsequent return to a patient. Typically, a system might utilize a negative pressure source for blood delivery and collection in a reservoir and use the force of gravity for return of the collected blood to the patient. Alternatively, instead of using gravity for blood return, for example, a roller pump or an intravenous pump might be used for reinfusion of collected blood to increase the rate of blood return to the patient. Another technique might be the delivery (under positive pressure) to the patient of blood previously collected from the patient or delivery (also under positive pressure) to the patient of donor blood. In each system, extreme caution must be exercised to prevent the inroduction of air into the patient return or delivery line, the presence of which could create an air embolism endangering the patient.
Disclosure of a blood collection and delivery apparatus can be found in U.S. Pat. No. 3,896,733. In this device, there is employed in each of two blood collection chambers a float valve which moves with the level of blood fluid in the chamber. The operation of the float valve is governed solely by the rise and fall of the level of blood in the chamber. Specifically, when the fluid in the chamber drops to the level of the valve seat at the bottom of the chamber, the valve sinks into sealing engagement with the valve seat to close off the fluid outlet from the chamber. The valve, which takes the form of a floating disc, is designed to prevent air from entering the chamber outlet. When fluid is again introduced into the chamber, the float valve is designed to rise with the rising fluid level.
A primary disadvantage of the aforementioned fluid outflow control system is that, should the floating disc not be properly seated, then air could enter the chamber outlet line leading to the patient. Improper seating could result should the floating disc become tilted or askew, for example, perhaps resulting from material buildup on the valve seat, material buildup on the blood surface or material buildup along the chamber wall. Coagulating blood could also cause disc tilting and result in an improper outlet seal. Due to the complex nature and makeup of blood, one or more of these undesirable situations could occur and result in air passage into the patient line, particularly when the floating valve depends solely upon the fluid level and incorporates no additional feature to positively urge the valve into sealing engagement with the valve seat.
The primary objective of the present invention is to advance the art field by providing a reliable reservoir fluid outlet control device, particularly a device suitable for controlling blood outflow from a blood collection reservoir, for releasably sealing the reservoir outlet against fluid passage therethrough. Accordingly, herein disclosed is a reservoir outlet control device which is especially designed and configured to provide a positive force for urging the outlet control device into a fluid sealing position at a predetermined fluid level in the reservoir and for preventing air entry into the patient delivery line.